This patch ensures '.desktop' files are picked up in the system profile
and not in the directories listed in $XDG_DATA_DIRS.  The latter includes
'gnome-session.desktop', which should be used if it's in
/run/current-system/profile, and only then.

Fixes <https://bugs.gnu.org/37831>.
diff --git a/daemon/gdm-session.c b/daemon/gdm-session.c
index 4b709731..3b83fcd3 100644
--- a/daemon/gdm-session.c
+++ b/daemon/gdm-session.c
@@ -362,16 +362,15 @@ get_system_session_dirs (GdmSession *self,
         GArray *search_array = NULL;
         char **search_dirs;
         int i, j;
-        const gchar * const *system_data_dirs = g_get_system_data_dirs ();
 
         static const char *x_search_dirs[] = {
                 "/etc/X11/sessions/",
                 DMCONFDIR "/Sessions/",
                 DATADIR "/gdm/BuiltInSessions/",
-                DATADIR "/xsessions/",
+                "/run/current-system/profile/share/xsessions/",
         };
 
-        static const char *wayland_search_dir = DATADIR "/wayland-sessions/";
+        static const char *wayland_search_dir = "/run/current-system/profile/share/wayland-sessions/";
 
         search_array = g_array_new (TRUE, TRUE, sizeof (char *));
 
@@ -380,11 +379,6 @@ get_system_session_dirs (GdmSession *self,
 
                 if (g_str_equal (supported_type, "x11") &&
                     (type == NULL || g_str_equal (type, supported_type))) {
-                        for (i = 0; system_data_dirs[i]; i++) {
-                                gchar *dir = g_build_filename (system_data_dirs[i], "xsessions", NULL);
-                                g_array_append_val (search_array, dir);
-                        }
-
                         g_array_append_vals (search_array, x_search_dirs, G_N_ELEMENTS (x_search_dirs));
                 }
 
@@ -392,11 +386,6 @@ get_system_session_dirs (GdmSession *self,
 #ifdef ENABLE_WAYLAND_SUPPORT
                 if (g_str_equal (supported_type, "wayland") &&
                     (type == NULL || g_str_equal (type, supported_type))) {
-                        for (i = 0; system_data_dirs[i]; i++) {
-                                gchar *dir = g_build_filename (system_data_dirs[i], "wayland-sessions", NULL);
-                                g_array_append_val (search_array, dir);
-                        }
-
                         g_array_append_val (search_array, wayland_search_dir);
                 }
 #endif
diff --git a/libgdm/gdm-sessions.c b/libgdm/gdm-sessions.c
index d8b4d5cd..7ed8de91 100644
--- a/libgdm/gdm-sessions.c
+++ b/libgdm/gdm-sessions.c
@@ -275,7 +275,7 @@ collect_sessions (void)
                 "/etc/X11/sessions/",
                 DMCONFDIR "/Sessions/",
                 DATADIR "/gdm/BuiltInSessions/",
-                DATADIR "/xsessions/",
+                "/run/current-system/profile/share/xsessions/"
         };
         const gchar *supported_session_types_env = NULL;
         g_auto (GStrv) supported_session_types = NULL;
@@ -288,29 +288,17 @@ collect_sessions (void)
         names_seen_before = g_hash_table_new (g_str_hash, g_str_equal);
         xorg_search_array = g_ptr_array_new_with_free_func (g_free);
 
-        const gchar * const *system_data_dirs = g_get_system_data_dirs ();
-
-        for (i = 0; system_data_dirs[i]; i++) {
-                session_dir = g_build_filename (system_data_dirs[i], "xsessions", NULL);
-                g_ptr_array_add (xorg_search_array, session_dir);
-        }
-
         for (i = 0; i < G_N_ELEMENTS (xorg_search_dirs); i++) {
                 g_ptr_array_add (xorg_search_array, g_strdup (xorg_search_dirs[i]));
         }
 
 #ifdef ENABLE_WAYLAND_SUPPORT
         const char *wayland_search_dirs[] = {
-                DATADIR "/wayland-sessions/",
+                "/run/current-system/profile/share/wayland-sessions/",
         };
 
         wayland_search_array = g_ptr_array_new_with_free_func (g_free);
 
-        for (i = 0; system_data_dirs[i]; i++) {
-                session_dir = g_build_filename (system_data_dirs[i], "wayland-sessions", NULL);
-                g_ptr_array_add (wayland_search_array, session_dir);
-        }
-
         for (i = 0; i < G_N_ELEMENTS (wayland_search_dirs); i++) {
                 g_ptr_array_add (wayland_search_array, g_strdup (wayland_search_dirs[i]));
         }
